In large part due to recency bias, my pick right now is probably Neil Gaiman and Terry Pratchett's Good Omens. That thing was devastatingly funny, and I basically didn't put it down from when I picked it up to when I finished it.
Off the top of my head, other notables are John Scalzi's Redshirts, the Hitchhiker's "trilogy" as a whole, and basically anything ever written by Jasper Fforde, but the Nursery Crime series in particular.
Off the top of my head, other notables are John Scalzi's Redshirts, the Hitchhiker's "trilogy" as a whole, and basically anything ever written by Jasper Fforde, but the Nursery Crime series in particular.